1. Field of the Invention
The invention relates to a transmission system which comprises a plurality of network elements which are arranged in a hierarchical, tree-like structure, and means for the management and allocation of resources to a network element.
2. Description of the Related Art
Such a transmission system is known from the publication "A primer on the T.120 Standard", DataBeam, 1995, P.5.
A transmission system of this kind is used, for example for communication and data transmission in a network consisting of a plurality of users and/or in distributed data bases. The management of resources in such distributed environments, i.e. the management, allocation and blocking of resources, is a decisive factor in respect of the speed and efficiency of a transmission system. Resources are, for example permissions which are available in the transmission system, for example the permission to speak in a communication system or the permission to use an arbitrary system element. A given quality of service may also be considered as a resource.
The infrastructure of known distributed transmission systems is organized in a hierarchical and tree-like manner. Starting from a main network element, in which the so-called top provider is localized, connections can be established with further network elements which are arranged at lower hierarchical levels. Network elements in which so-called providers are located offer, in addition to other services, the functionality for the management of resources in the transmission system. A network element can claim a resource as soon as a connection has been established between this element and the network element managing the resource. The path through the tree structure thus formed, extending from a first network element which manages a resource to a second network element which claims the resource offered, is referred to as a resource path.
The allocation and the possession of a resource can be described in abstract terms as the allocation and the possession of a token. In known transmission systems the number of a token and the possessor are stored by appropriate means in the transmission system. In the case of distributed storage, storage takes place in each network element. A change of the state of a resource, i.e. when the possessor of a token changes, when a token is released or surrendered, may cause a plurality of updating messages between all network elements and could lead to a different state of the information in different network elements. Central storage of the information, however, has the drawback that each information concerning a resource, for example the requesting of a resource, must be addressed to the top provider and possibly transported further to the central storage element arranged in a different location. In large transmission systems this leads to very long response times for a resource request and overall to a reduction of the efficiency of the transmission system.